This invention pertains to vacuum cleaners. More particularly, this invention relates to a two-stage inertial particle separator for vacuum cleaners.
Cyclone separators remove solid particles such as dust from a flow of air or other gas by subjecting the flow to a spiral-like motion during which centrifugal force urges the denser particles to move outwardly with respect to the gas in which they are suspended. Cyclonic particle separators are known in a variety of environments. For example, air precleaners are used for removing particles from the air prior to introducing the air, through an air cleaner or filter, to a carburetor or an air intake structure of an internal combustion engine. In the petroleum industry, fine catalyst dust is separated from the large stream of hot flue gas leaving a regenerator vessel of a fluid catalytic cracking unit by centrifugal separation apparatus. Cyclonic separators are also employed to separate solid particles from a flow of gas in a variety of other environments.
Conventional vacuum cleaners employ a filter bag for separating dirt and dust entrained in air which is picked up by a suction nozzle of the vacuum cleaner. More recently, cyclonic vacuum cleaners have become known. In these devices, one or more cyclones are employed to separate dirt and dust particles from the air. The dirt laden air enters the top of a dust canister tangentially and is caused to swirl. The larger particles fall to the bottom of the canister. The airflow then rises along the longitudinal axis of the canister towards a cap that is connected to a U-shaped tube. The U-shaped tube redirects the airflow enabling it to tangentially enter an inner cyclone having a frusto-conical shape. The air is then caused to swirl again and smaller dust particles which remain entrained in the air will fly radially outwardly and slide downwardly along the walls of the inner frusto-conical chamber to a dust collecting chamber at the bottom. One known such vacuum cleaner is disclosed in U.S. Pat. No. 4,853,011. However, this known cyclonic vacuum cleaner design is not optimum.
Another known vacuum cleaner employing cyclonic airflow is disclosed in U.S. Pat. No. 3,877,902. This vacuum cleaner, which is a wet/dry tank type cleaner has a container with an upper part provided with an inlet opening for dust laden air or liquid and a discharge opening for clean air. A lower part of the container collects separated dust or separated liquid. A generally vertically disposed cyclone separation unit is located in the container and is operatively connected to the inlet opening. A motor fan unit provided in the container moves air through the container. A filter is mounted between the cyclone separator and the motor fan unit so that air flows out of the cyclone separator unit through the filter and to the motor fan unit. This known cyclonic flow vacuum cleaner also does not have an optimum design.
Another known cyclonic flow vacuum cleaner is illustrated in U.S. Pat. No. 3,425,192. That device shows what appears to be a stationary housing with a three-stage vacuum cleaning system having vertically arranged lower, middle and upper housing sections. Air enters the lower housing section tangentially and is caused to swirl above the open upper end of an inverted frusto-conical member. Heavier dirt and the foreign matter falls downwardly into a relatively large dirt receptacle. Thereafter, the air flows upwardly through a central cylindrical sleeve to the upper ends of a plurality of second stage cyclone separators. In the second stage, a plurality of helical vanes cause the dirt to swirl in a downward helical direction within tubular members. Finer dirt and foreign matter particles fall downwardly into a second dirt collecting pan. The now twice-cleaned air is pulled upwardly through central tubes and through a final filter sheet. Thereafter, the air is pulled through a vacuum pump and discharged from the vacuum cleaning system. This system is disadvantageous from the standpoint that it is very large and appears to be designed for stationary whole house vacuum systems instead of ambulatory vacuum cleaners.
Another known cyclonic vacuum cleaner is disclosed in European Publication No. EP 0 885 585 A1. This patent document relates to a multi-stage vortex arrangement with a built-in recirculation or feedback loop. In a first stage cyclone separator, approximately 90% of the dirt and other particles is spun out. Semi-clean air is then drawn into a second stage involute separator which induces a high velocity vortex to concentrate finer dirt particles into about 20% of the airflow. That portion of the airflow is then cleaned using a third stage miniature cyclone. Transport air from the third stage is vented to an outlet port along with the second stage outlet air. This design is disadvantageous as being too complex.
Accordingly, it has been considered desirable to develop a new and improved vacuum cleaner which would overcome the foregoing difficulties and others while providing better and more advantageous overall results.
A vacuum cleaner for centrifugally separating dirt from the air in which it is entrained is provided.
More particularly, the vacuum cleaner comprises a housing having a separation chamber and a nozzle communicating with the separation chamber. An air path directs the dust entrained air to the separation chamber. The separation chamber has two stages. The first stage is formed by a housing having an airflow path which guides dust entrained air in a substantially circular flowpath. The flowpath has a radially inner opening through which air that has been separated from heavier dust particles enters the second stage. The heavier dust particles continue along the substantially circular flowpath and fall into a first portion of a dust container. The second stage includes a centrally positioned hub and a plurality of vanes extending radially outward from the hub. The vanes cause the air to swirl. In the second stage the lighter dust particles still remaining entrained in the air are flung radially outwardly and fall into a second portion of the dust container. The now twice-cleaned air flows axially downward and radially inward to exit through an outlet tube out of the dust container.
According to another embodiment of the present invention, a vacuum cleaner is provided.
In accordance with this aspect of the invention, the vacuum cleaner comprises a housing and a nozzle in fluid communication with the housing. A suction source is held by the housing and the nozzle is in fluid communication with the suction source. A dust cup is selectively secured to the housing. The dust cup comprises an inlet in fluid communication with the nozzle, a first inertial dust separation stage positioned downstream from the inlet and a first dust containing chamber located adjacent the first inertial dust separation stage for holding the dust separated by the first inertial dust separation stage. A second inertial dust separation stage is located downstream from the first inertial dust separation stage. A second dust containing chamber is located adjacent the second inertial dust separation stage for holding dust separated by the second inertial dust separation stage. An outlet is located downstream from the second inertial dust separation stage.
One advantage of the present invention is the provision of a new and improved vacuum cleaner which can be a tank type cleaner, a canister cleaner, an upright cleaner or even a central vacuum cleaner.
Another advantage of the present invention is the provision of a two-stage inertial particle separator for a vacuum cleaner. In a first particle separation stage, heavier dust particles are separated from air which is caused to flow radially inwardly. In a second particle separation stage, the remaining dust particles are caused to move radially outwardly while the now twice-cleaned air flows towards a central axial opening.
Still another advantage of the present invention is the provision of a vacuum cleaner in which two stages of inertial separation take place in a selectively removable dust container, thereby eliminating the need for a filter bag. Such inertial separation can be caused by sudden changes in the direction of air flow, by a rotation of the air as it flows caused either by a set of vanes over which the air flows or by a tangential inlet opening for air flowing into a chamber.
Yet another advantage of the present invention is the provision of a vacuum cleaner with a two stage inertial particle separation system in which a first separation stage includes a set of louvers located in an opening positioned radially inwardly from an air flow path. The direction of air flow is suddenly changed by the opening and the louvers but centrifugal force exerted on particles entrained in the air prevents the particles from entering the second stage through the set of louvers as the air enters.
Still yet another advantage of the present invention is the provision of a vacuum cleaner with a two stage inertial particle separation system in which a second stage includes a deflector with a set of vanes which causes air to spin urging entrained particles radially outwardly while air leaves via a centrally located air exit tube spaced from the deflector.
An additional advantage of the present invention is the provision of a vacuum cleaner having a dust cup with two chambers. A radially outer chamber holds heavier dust particles separated by the first stage of an inertial particle separation system of the vacuum cleaner. A second radially inner section of the dust cup holds lighter dust particles separated by the second stage of the inertial particle separation system of the vacuum cleaner.
Still other benefits and advantages of the invention will become apparent to those skilled in the art upon a reading and understanding of the following detailed specification.